. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 462 Prof. P. M. Duncan and Mr. W. P. Sladen on to warrant its removal, in our opinion, from that species, even as a provisional variety. In some cases great irregularity is exhibited in the mouth- papillae, one abnormal example being particularly worthy of notice. In the Oijliioglyphce the innermost mouth-papilla generally stands immediately over the teeth, and might be easily mistaken for a tooth, being, in fact, affixed to the tooth- plate and not to the lateral plates. In 0
. The Annals and magazine of natural history; zoology, botany, and geology. Natural history; Zoology; Botany; Geology. 462 Prof. P. M. Duncan and Mr. W. P. Sladen on to warrant its removal, in our opinion, from that species, even as a provisional variety. In some cases great irregularity is exhibited in the mouth- papillae, one abnormal example being particularly worthy of notice. In the Oijliioglyphce the innermost mouth-papilla generally stands immediately over the teeth, and might be easily mistaken for a tooth, being, in fact, affixed to the tooth- plate and not to the lateral plates. In 0. Sarsit, as well as in other members of the genus, two additional papilla? are generally associated with it, one on either hand, and are in like manner borne by the ossicle upon which the teeth are placed. In consequence of this arrangement it has long seemed probable to one of us that these subdental papillee should be regarded as tooth-papilla (of which they are in truth the homologues) rather than as mouth-papilla3, so-called, along with which they are commonly counted. One of the speci- mens taken in Discovery Bay throws considerable light upon this question. In this individual the dental armature consists of four teeth regularly superposed, following upon which, and occupying the same breadth as a tooth, are three ossicles, which fit to one another wedgewise with sloping- sides. Then come two which fit together and correspond in their shape with the irregularities of the upper and under tier, which latter consists of from three to five compact close-fitting papillae; and these again are succeeded by three or four (in some rays five) moderately long, round-tipped, smaller papillae, the whole form- ing a compact mass suggestive, in the highest degree, of ordi- nary tooth-papillae, such as occur, for instance, in Ophiothrix ; and yet in every detail, even to mea- surements, the specimen con- forms to the diagnosis of Opliio- glypha Sarsii, This individual has a disk-diameter
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